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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study according to OECD guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report date:
2014

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrahydro-2-isobutyl-4-methyl-2H-pyran
EC Number:
236-770-1
EC Name:
Tetrahydro-2-isobutyl-4-methyl-2H-pyran
Cas Number:
13477-62-8
Molecular formula:
C10H20O
IUPAC Name:
4-methyl-2-(2-methylpropyl)oxane
Details on test material:
- Name of test material (as cited in study report): Dihydrorosenoxid
- Physical state: liquid / colorless, clear
- Analytical purity: 99.5 corr. area% as a sum of two isomers
- Lot/batch No.: 11260/14 Versuch 19 Fraktion 6-7,9-13,14
- Expiration date of the lot/batch: 03 April 2016
- Stability under test conditions: stable
- Storage condition of test material: at room temperature

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
Municipal activated sludge from the wastewater treatment plant of Mannheim, Germany
was collected on 19 May 2014 from the aeration tank of the plant. A suitable aliquot of
the suspension was sieved by a finely woven mesh with a mesh size of about 1 mm. To
reduce the content of inorganic carbon in the blank control the activated sludge
suspension was aerated with carbon dioxide free air for about 48 hours at 22 ± 2° C.

- Preparation of inoculum for exposure: At the day of exposure the aeration was stopped and the sludge was allowed to settle.
The supernatant was discarded and the residue of the sludge suspension was filled up
with drinking water. The sludge of the suspension was adjusted to a concentration 800
mg/L of dry weight. Aliquots of 0.5 mL were added to the test vessels to obtain a sludge
concentration of 4 mg/L dry substance in the test assays.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
20 mg/L
Based on:
other: TOC
Initial conc.:
26 mg/L
Based on:
test mat.
Details on study design:
TEST CONDITIONS
- Composition of medium: complies with test guideline OECD 310
- Test temperature: 22 ± 2 °C.
- pH:A pH- shift in the test vessels, induced by addition of the test substance to the test
medium was checked in a preliminary test. No shift of the pH-value was detected.
The pH-value from the mineral test medium was therefore assumed for the test
assays at start of exposure.
This pH-value of the mineral medium after correction was 7.4.

TEST SYSTEM
- Culturing apparatus: 160 mL incubation bottles filled up to a
volume of 100 mL
- Number of culture flasks blank control assays (BC): 29
- Number of culture flasks test substance assays (TS): 31
- Number of culture flasks inhibition control test assays (IH): 29
- Number of culture flasks reference substance assays (RS): 17
- Number of culture flasks assays for abiotic control (PC): 5
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance: The bottles were closed with
butyl rubber septa gas tight.
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: At the sampling days three bottles of each test assay were sacrificed.
1 mL 7 molar sodium hydroxide solution was injected with a syringe trough the septum in
each test bottle. The bottles were shaken for about one hour. The carbon dioxide in the
headspace, evolved by biological processes, is solved in the alkaline solution. For the
measurement at the end of exposure five test substance assays were prepared. The
single values of these test assays were used for mean value calculation of the
biodegradation degree with a limit of confidence limit of 95 %. The inorganic carbon
content of the sodium hydroxide solution used for the alkalization of the test assays was
checked and considered at the evaluation. The bottles were opened and the amount of
Total Inorganic Carbon (TIC) was determined with a carbon analyzer. The measured TICvalues
were compared with the added amount of TOC and expressed as biodegradation
degree and plotted by a biodegradation curve.

SAMPLING
- Sampling frequency: every 3-4 days
- Sample storage before analysis: The samples were analyzed on the day of sampling
without further treatment.


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
Reference substance
Reference substance:
aniline

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
18
St. dev.:
5
Sampling time:
28 d
Remarks on result:
other: CO2 evolution measured as TIC/TOC
Details on results:
Dihydrorosenoxid was not readily biodegradable in this test

BOD5 / COD results

Results with reference substance:
Degree of biodegradation of the reference substance after 14
days, mean value: 72 % TIC/TOC

Applicant's summary and conclusion

Validity criteria fulfilled:
yes